Reference may be had to the assignee's following patents:
3,206,065 PA1 3,245,135 PA1 3,250,870 PA1 3,264,860 PA1 3,298,217 PA1 3,310,301
Which shows the most pertinent prior art known at the time of the present invention. The art which was cited in each of the above patents provides further prior art disclosures.